CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 3, May/June 2022 128 AFRICA The use of strain-gauge plethysmography in the functional assessment of chronic venous disease: five-year experience at a single centre Hamit Serdar Başbuğ, Hakan Göçer, Kanat Özışık Abstract Objective: Plethysmography can be used in the diagnosis and evaluation of chronic venous disease in the lower extremities. This study aimed to evaluate the applicability and reliability of strain-gauge plethysmography (SDP) in the functional assessment of chronic venous disease. Methods: This descriptive study was conducted between 2016 and 2021 at a single centre. Four hundred and thirtytwo patients with symptomatic chronic venous disease were included in the study. All participants were diagnosed initially with Doppler ultrasonography. SGP was then performed to evaluate venous outflow capacity, venous reflux and muscle pump function. Results: The average age was 45.16 ± 12.54 years (median age 46 years; range 20–78 years), and 239 (55.3%) women and 193 (44.7%) men were included in the study. The age groups, diagnosis, pathological distribution and risk factors were quantitatively determined according to gender. Localisation and lateralisation statistics of the pathologies are given. SGP measurements, including venous volume (V), venous emptying (VE), expelled volume ratio in four seconds (EV4/V), half refilling time (t½) and refilling volume (RV) of each lower extremity, were done individually to compare the involved extremity with the normal contralateral side. SGP measurements of each affected lower limb were also compared separately by gender, age group and disease onset. The correlation between t½ values and skin discolouration or oedema of the affected limb was examined. Finally, receiver operating characteristic curve analyses of the V, VE, EV4/V, t½ and RV values were done, and the cut-off values of each parameter were defined accordingly. Conclusion: High reliability and consistent results indicate that SGP is a practical and sensitive test for quantitative functional assessment of patients with chronic venous disease. It can be used as an effective method in diagnosing and following up chronic venous disorders. As there are no currently accepted cut-off values, we suggest that ours can be used as new reference values for SGP measurements. Keywords: plethysmography, diagnostic techniques, cardiovascular, venous insufficiency, venous thrombosis Submitted 17/5/21, accepted 9/10/21 Published online 17/1/22 Cardiovasc J Afr 2022; 33: 128–136 www.cvja.co.za DOI: 10.5830/CVJA-2021-050 Chronic venous disease (CVD) is a term that indicates a spectrum of venous disorders ranging from asymptomatic valvular incompetence to varicose veins, chronic venous insufficiency (CVI), deep venous insufficiency (DVI), deep-vein thrombosis (DVT), skin pigmentation and chronic leg ulceration.1 CVD is the leading chronic disorder and a substantial cause of morbidity in the Western world.2 The prevalence is around 30%, and it is also costly, taking approximately 2% of the overall healthcare resources alone.3 CVD symptoms are leg pain, heaviness, oedema, varicose lesions, skin changes and unhealing stasis ulcers, all of which are caused by impaired venous drainage, leading to venous hypertension.4 Although history taking and physical examination are often sufficient for the diagnosis, patients with CVD undergo various imaging test procedures to assess the extent of the disease and to constitute a treatment plan.5 Doppler ultrasonography (DUS) has become the reference imaging test as it points to the exact anatomical location of venous reflux, measures the reflux quantitatively, and is a non-invasive test.6 However, the clinical picture can differ regarding the anatomical location, for example, an occluded iliac vein or the presence of a vena cava lesion.7 Invasive tests, including computerised tomography venography and magnetic resonance venography, then come into consideration but are rarely preferred.8,9 There is increasing attention on functional tests that can quantitatively define the haemodynamic pathology, giving further information obtained by imaging techniques.5 Additionally, access to a radiology service may sometimes be difficult or delayed. The problem of reaching trained personnel is often encountered in remote settlements. Therefore, a practical, non-invasive diagnostic test other than DUS imaging should be established to minimise false-negative examinations while reliably excluding or confirming an accurate diagnosis in a busy, remote medical unit.10 Alternative tests for venous function are strain-gauge plethysmography (SGP), air plethysmography (APG), and photoplethysmography, where SGP and APG can quantitatively determine both venous outflow and venous valve function.11 SGP is a non-invasive test for CVD, determining the venous capacitance, venous outflow rate, and venous refilling time (a measure of valvular competence).12 The procedure is also simple, painless and easily performed in about 20 minutes, with a rapid result.10 The strain gauge is wrapped around the larger circumference of the calf. Volumetric changes in calf circumference cause proportional Department of Cardiovascular Surgery, Faculty of Medicine, Kafkas University, Kars, Turkey Hamit Serdar Başbuğ, MD, s_basbug@hotmail.com Hakan Göçer, MD Kanat Özışık, MD
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